A production line of the conventional type in the paper tissue industry for obtaining embossed products such as the aforementioned ones, is schematically illustrated in FIG. 1. A reel of a multiweb paper band, for example with three/four webs, indicated with B, is unrolled in an unwinding device 1. The unrolled band N, through deviation rolls 2, is supplied to a roller press 3 and therefrom to a cylinder embossing group 4, comprising a cylinder with some in-relief design pattern (pressing cylinder) and a first contrast cylinder for keeping the band pressed against the pressing cylinder in order to emboss the design pattern thereon. In the prior art the cylinders are both made of metal in the typical case of tissue handkerchiefs and napkins, while in case of paper towels and toilet paper the two cylinders are respectively made of rubber and steel. The exiting embossed band is thus fed, through deviation rolls 5, to a folding equipment 6, as shown in FIG. 1, in which the tissue handkerchiefs/napkins are obtained from the band by cutting and folding, or to a rewinder, not shown, for producing toilet paper or paper towel rolls. In the same FIG. 1, below the diagram of the production line as described, there is schematically shown the surface of the band (N1) exiting from the unwinding device 1, of the band (N3) exiting from the roller press 3 and of the band (N4) exiting from the embossing group 4. In the case here exemplified, the embossing, showed using a grey hatching and indicated with 7, is extended over the entire surface, except for a number n of equal and regularly spaced regions (four quadrilateral areas in the illustrated case), indicated with 8. Thus, the resulting paper handkerchief/napkins, once cut from the band, will typically have a central non-embossed area (corresponding to a region 8), and an embossed peripheral frame.
As known to those skilled in the art, embossing in the aforementioned products not only serves a decorative purpose, but also contributes to keep the webs which form these products together. This aspect, i.e. the capacity of the webs to remain joined together during use, is important for determining the quality of the product. The adhesive effect between the webs however depends on the type of paper used, and with less soft and yieldable paper, which may advantageously be used for obtaining less expensive products, this effect reduces remarkably, hence the structure of the end product is unstable. In these cases the use of a bonding agent suitably distributed between the webs in the areas subjected to embossing may help overcome the problem, but the current production lines do not allow a selective distribution of the bonding agent which would end up inevitably deposited even in the non-embossed areas thus stiffening the end product and deteriorating the quality thereof. The need for ensuring high adhesion of the webs also affects the maintenance of the embossing equipment. Actually, ensuring high quality standard as far as the adhesion of the webs is concerned, requires maintaining high pressure between the two metal cylinders, hence leading to quick wear of the same and the need of having to replace them often (usually every six months), thus increasing the production costs. A similar problem arises should one want to selectively print a coloured drawing or motif, a writing or anything else on the non-embossed areas or on the embossed areas of a product. Even in this case the current production lines do not allow for selectively printing the embossed areas or the non-embossed areas, in normal cases the embossed areas of the product completely surrounding the non-embossed areas.